The hydrogen fuel cell has been attracting attention as a next-generation power source with low environmental load and high efficiency. The hydrogen fuel cell performance depends on a proton conductor, which transport the generated protons from the anode to the cathode side electrodes during its catalytic reaction.
Currently, polymer proton exchange membranes (PEM) are widely used as a proton conductor for fuel cells. However, PEM is not stable material in term of long-operation time at high temperature, which is required for faster proton mobility as result PEM is deteriorated and fuel crossover effect appears which latter leads to low device efficiency. There is fast-growing demand for hydrogen fuel cells as a next-generation power source, and the present invention has a great potential to replace PEM fuel cell in term of highly stable proton conductor that allows improving fuel cell performance. On the other hand, recent advances in nanotechnology have enabled to create functional devices, which are based on nanospace and provides an extraordinary high surface effect. With consideration of that, new ion-conduction devices are expected in the near future.
In view of such problems, Chinen et al. found that the proton diffusion coefficient of water increases by approximately one order of magnitude in a glass made nano channel (with its size of several hundred nanometers) and also demonstrated that glass made nano channel is mechanically/chemically stable and can be used as proton conductor with analogue to conventional PEM, but operated at ambient temperature condition (Non Patent Literature 1: Chinen et al., Angew. Chem. Int. Ed., 2012).
Tsukahara et al. reported increasing of proton conductivity in nano channel (with its size of a few hundreds nanometers) where water molecules are confined in such space and 3 phase model where proposed and suggests that structured water in 50 nm in the vicinity of a glass wall surface of a nano channel contributes to the enhanced proton diffusion (Non Patent Literature 2: Tsukahara et al., Angew. Chem. Int. Ed., 2007).